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In short- why should we care about IOPS?In depth- this is what i don't understand:I've read quite a number of articles and forum posts regarding this issue and couldn't come to a conclusive answer.Basically, in order to know if the IOPS is a limitation one would need to know how many IOPS are needed by the machine.I couldn't find any relevant information on that apart from Database info like this: http://blog.unidesk.com/do-vdi-iops-matter which states 2000 IOPS as a typical workload.This article states that IOPS in flash (SSD) is practically unlimited and since latency is also not an issue in SSD's, it seems that the only relevant measurement is Throughput.https://flashdba.com/2013/06/27/storage-myths-iops-matt...The comments are really interesting too.This also seem to follow the same lines: https://storageswiss.com/2015/02/23/what-are-iops-and-s...The thing is, all these articles are from professional storage point of view and they talk about it in the relation with an array of physical disks in a data center and such.What I'd like to know is weather these figures means anything to mortals?I mostly do video editing and grading.I tend to think that the following is an ideal setup for me (drives wise)1. OS and Programs- 250GB SSD2. Media cache- 250GB SSD3 .Media drive for hot projects- 1tb SSD or 2 500GB SSD's in RAID 04. Data drives (backups and all other stuff)- FreeNAS server with 6 8TB NAS DrivesLet's concentrate on the SSD's.On the OS drive and the Media cache drive I'll be doing mostly small reads and writes.On the Media Drives I'll be doing very large Sequential Reads (Video files).Currently I have only one SSD which is used for OS, Programs, and media cache. This is on a Intel 520 series 240GB drives which is rated at:Sequential Read (up to) 550 MB/sSequential Write (up to) 520 MB/sRandom Read (8GB Span) (up to) 50000 IOPSRandom Write (8GB Span) (up to) 60000 IOPSFor comparison, the Samsung 850 EVO 250GB specs are this:Up to 540 MB/s Sequential ReadUp to 520 MB/s Sequential Write Up to 97,000 IOPS Random ReadUp to 88,000 IOPS Random WriteI want to add the next SSD on the list which will only serve for media cache. Later on (budget you know) I'll add the large 1tb hot projects media drive.I'm thinking of getting the Intel 600p Series 256GB M.2 SSD which is rated:Sequential Read (up to) 1570 MB/sSequential Write (up to) 540 MB/sRandom Read (8GB Span) (up to) 71000 IOPSRandom Write (8GB Span) (up to) 112000 IOPSRegarding all the information above, will it be better suited for the OS, for the Media Cache, or for Media drive?And could somebody please explain why everybody is talking about IOPS? How is that important? How is that a limitation in this kind of setup?Is there an application that needs 50,000 IOPS?? What is a normal IOPS rate?This also begs the question, why should we consider "Pro" drives like the Samsung 850 Pro or the Sandisk Extreme Pro when their throughput is essentially the same?Besides reliability, what's to gain from this drives in terms of performance?Sorry for the long post...Eli

Hello All, just joined the forum as I have a couple of questions about or san and wondered if we are getting the best from it. I have tried to give as much information as possible without every possible setting (I'll wait for requests for them). in short I think I might be having throughput/iop performance issues for my VM's. not sure if its iSCSI network related or san related or VMware related. or maybe I have none and was just expecting more.
The Problem
We recently had a company in to upgrade our infrastructure (we were still server 2003). We are noticing a bit of a lag in one program. The program in question (an ERP system) is a new program for us so we are not sure if its the hardware or the software as we have no benchmarks on either.
Information
3 hosts (HP DL380p Gen8 dual 3ghz 10 core cpu, 64gb mem) with latest esxi on SD card. no disk in any host.
Cisco (C2960x) stacked switch connecting all the host for network, management, vmotion, etc..
The iSCSI network is then on 2 separate cisco switches (non stacked) again C2960x
we currently only have 6vms setup (2 DCs, 1 exchange, 1 vcenter, 1 ERP application, 1 ERP DB ) the ERP software is not used by anyone yet.
SAN is 1 HP MSA 1040 (dual controller with dual 1GB on each) I believe 2GB cache on each controller. + 1 HP D2700 enclosure.
the disks are as follows:
Name Size RAID Disk Type Current Owner Disks vDisk01 2398.0GB RAID50 SAS A 6 (10k 600GB) vDisk02 4196.5GB RAID5 SAS B 8 (10k 600GB) vDisk03 3597.0GB RAID5 SAS A 7 (10k 600GB) vDisk04 2996.8GB RAID50 SAS B 12 (15k 300GB)
The ERP is on vDisk04 (only the application and db vm are on this).
Here are some stats from CrystalDiskMark:
Results
This is from one of the erp vm's on vDisk04
Sequential Read : 108.898 MB/s
Sequential Write : 107.679 MB/s
Random Read 512KB : 102.853 MB/s
Random Write 512KB : 98.401 MB/s
Random Read 4KB (QD=1) : 8.630 MB/s [ 2107.0 IOPS] Random Write 4KB (QD=1) : 5.251 MB/s [ 1281.9 IOPS]
Random Read 4KB (QD=32) : 98.198 MB/s [ 23974.2 IOPS] Random Write 4KB (QD=32) : 49.038 MB/s [ 11972.3 IOPS]T
Test : 500 MB [D: 8.1% (16.3/200.0 GB)] (x5)
OS : Windows Server 2012 Server Standard Edition (full installation) [6.2 Build 9200] (x64)
running crystaldiskmark gives almost identical results from any vm (no matter the vdisk the vm is on) I would of expected slightly different results due to the raid.
we also have 1 host running server 2012 native and ran crystaldiskmark on vDisk03 and get slightly improved results. So this leads me to question the VMware settings being a slight issue possibly? also not sure if I should be seeing better throughput/iops in general or if these figures are reasonable?
This is the other result:
Sequential Read : 205.442 MB/s
Sequential Write : 189.707 MB/s
Random Read 512KB : 172.833 MB/s
Random Write 512KB : 169.600 MB/s
Random Read 4KB (QD=1) : 9.021 MB/s [ 2202.3 IOPS]
Random Write 4KB (QD=1) : 6.164 MB/s [ 1505.0 IOPS]
Random Read 4KB (QD=32) : 136.312 MB/s [ 33279.2 IOPS]
Random Write 4KB (QD=32) : 50.407 MB/s [ 12306.4 IOPS]
Test : 500 MB [E: 22.5% (752.6/3349.4 GB)] (x5) OS : Windows Server 2012 Server Standard Edition (full installation) [6.2 Build 9200] (x64)
Hopefully some intelligent knowledgeable person on here can help me troubleshoot where any issues may be or can tweak a few settings to get some better performance (if any). or failing that I can pinpoint the issue to be the ERP software and know my hardware is all fine. I hope the limitation isn't the new infrastructure that's been implemented.
Thank you in advanced.
EDIT:
Forgot to mention I have roundrobin / MPIO setup. Thanks again.